Full stroke energized rotary magnet



J1me 1953 H. J. MOCREARY 3,092,737

FULL STROKE ENERGIZED ROTARY MAGNET Filed May 5, 1960 INVENTOR. HaroldJ. M: Oreo/y United States Patent Oflfice 3,092,737 Patented June 4,1963 3,092 737 FULL STROKE ENERGIiED ROTARY MAGNET Harold J. McCreary,Canoga Park, Calif., assignor to Automatic Electric Laboratories, Inc.,Northlake, Ill.,

a corporation of Delaware Filed May 3, 1960, Ser. No. 26,639 4 Claims.(Cl. 307-112) This invention relates to an interrupter arrangement foran electromagnetic device, and more particularly, to an improved circuittor controlling the interrupting action of a stepping switch, forexample, of the type used in telephone switching systems.

One of the objects of this invention is to insure completion of both theoperating and release strokes of the armature of an electromagneticdevice.

More specifically, an object of this invention is to keep the magnet ofan electromagnetic device, such as that of a stepping switch, energizedthrough most of the operating stroke of the armature, while maintainingthe magnet de-energized through most of the release stroke.

Another object of this invention is to provide a novel interruptercircuit for a stepping switch which will be simple and inexpensive tomanufacture.

Generally speaking, the principal feature of the invention is theutilization, for the control of the magnet of an electromagnetic devicesuch as a stepping switch, of a bistable electronic switching meanswhose state is in turn controlled by contacts of the magnet.

Briefly, the embodiment of the invention described herein comprises astepping switch having b ank contacts, wipers, a motor magnet with anarmature having selfinterrupter contacts, and a linkage for stepping thewipers over the bank contacts. A thyratron tube is used in combinationwith the stepping switch to provide a bistable switching means forcontrolling the operation of the motor magnet. The thyratron tube iscontrolled by the self-interrupter contacts of the armature in such away that this tube keeps the motor magnet energized throughout virtuallyall of its operating stroke and de-energized throughout virtually all ofits release stroke.

Although a preferred embodiment of the invention is herein disclosed anddiscussed, it is to be understood that this invention is not limited tothis embodiment, but may easily be adapted to other uses either in itspresent form or by slight alterations.

The single FIGURE of the drawing shows this preferred form of theinvention. Referring to the figure, the arrangement disclosed consistsof a stepping switch 24 having a contact bank 18, wipers 19 to engagethe contacts of this bank, and a motor magnet having an armature 21. Astart contact 12 is interposed between one terminal of the motor magnetand battery and operated by start relay 22. Break contacts 20 and Y areoperated by the armature, and the armature actuates a stepping mechanismto step the wipers responsive to the armature movement. This steppingmechanism comprises a ratchet wheel 26, a pawl 25 engaging said ratchetwheel, an armature spring 23, and a detent 14 to prevent wiper rotationin the reverse direction. The stepping switch may be either of thedirect-stepping or the indirectstepping type, both of these types beingwell known in the art. The arrangement also includes a thyratron tube 11 having a cathode 16 serially connected with the Y contact and themotor magnet, an anode 17 connected to ground, a control grid connectedto contact 20 through a resistor R and connected to negative batterythrough a resistor R and an optional shield grid 13 connected to thecathode lead. A resistor R placed between ground and the other terminalof the motor magnet allows the motor magnet to be pre-energized whenstart contact 12 is closed.

Contact 20 is adjusted so as to open shortly after the beginning of theoperating stroke, and consequently this contact recloses shortly beforecompletion of the return stroke. Contact Y is adjusted to open nearcompletion of the operating stroke and hence recloses shortly after thebeginning of the return stroke.

Thyratron tube 11 fires or begins conducting only when both contacts areclosed. Due to the above adjustments of contacts 20 and Y, thiscondition is met once each cycle shortly before completion of therelease stroke. Once fired tube 11 will continue to conduct as long asthe Y contact remains closed, that is, tube 11 will be extinguishedshortly before the end of the operating stroke.

Now a relationship between the operation of tube 11 and the function ofthe stepping switch can be established. In the normal state of thesystem, magnet 10 is in the Lin-operated condition and contacts Y and 20are closed. Start relay 22 is operated by known methods (such as a linerelay in a telephone subscribers circuit) to close start contact 12.When closed, start contact 12 completes the pre-energizing circuit formagnet 10 extending through resistor R to ground, the current flowing inthe circuit, however, being insufiicient to cause the operation ofmagnet 10. Closure of start contact 12 also extends battery through thewinding of motor magnet 10, through the Y contact, hence to cathode 16.Control grid 15 normally has a relatively positive bias while anode 17is connected to ground. In this condition, ionization occurs causing thegas discharge tube 11 to fire or begin conducting.

It will be seen from the drawing that the main conducting path includingcathode 16 and anode 17 extends serially both through contact Y andthrough magnet 10 to battery. Thus motor magnet 10 is now sufficientlyenergized through this path to attract its armature. Contact 20 breaksas the armature starts its operating stroke, biasing control grid 15negative. The negative bias on control grid 15 has no effect at thistime however. The Y contact breaks shortly before completion of theoperating stroke, removing battery from cathode 16. As a result, tube 11de-ionizes, opening the last-mentioned circuit, thus substantiallyde-energizing the motor magnet.

The armature now starts its release stroke and the Y contact immediatelyre-closes. Since the control grid '15 remains biased negative by opencontact 20, the tube will not conduct and motor magnet 10 will remainsubstantially de-energized throughout most of the release stroke.Contact 20 recloses shortly before completion of the release stroke,biasing the control grid 15 positive.

At this time control grid 15 has a positive :bias and battery haspreviously been extended to cathode 16 by the closing of the Y contact.Thus, ionization again occurs and tube 1 1 fires, reoperating the motormagnet 10 and starting the armature on its operating stroke again. Thiscycle will repeat itself until the circuit is opened by known methods atstart contact 12. On each cycle stepping switch 214 takes one step underthe control of the stepping mechanism in the Well-known manner.

It should be noted that in the disclosed embodiment, a gas dischargetube is used in combination with the selfinterrupter contacts on thearmature of a motor magnet to control the energization of this magnet.This type of control achieves nearly instantaneous response of the motormagnet to its control contacts 20 and Y. More particularly, there is notime lag between closing the circuit to fire the gas discharge tube nearthe end of the release stroke and energization of the motor magnet.There is also no time lag between opening the circuit near the end ofthe operating stroke and the extinguishing of the tube and de-energizingof the magnet. In this manner, completion of both the operating andrelease strokes of the armature and hence completion of each step of thestepping mechanism of the switch is fully insured.

What is claimed is:

1. In combination with an electromagnetic device having a magnet, anarmature actuated by said magnet and first and second contactscontrolled by said armature: a self interrupting arrangement for saidmagnet insuring completion of both the operating and release stroke ofsaid armature, said arrangement comprising a source of potential, abistable switching means having a control electrode, output electrodes,and a circuit including said output electrodes, said magnet, and saidsecond contact, sai-d first contact being arranged to operate near theend of said release stroke to connect said control electrode to saidpotential, said bistable switching means being switched to one of itsstates in response to the last mentioned connection to cause said magnetto be energized under the control of said output electrodes, and saidsecond contact being arranged to operate near the end of the operatingbank contacts; and a stepping mechanism linked to said armature forstepping said wipers over said bank contacts.

3. The combination as claimed in claim 1, wherein said bistableswitching means is a thyratron tube.

4. The combination as claimed in claim 3, wherein said thyratron tube isfired responsive to said first contact impressing said source ofpotential on said control electrode, and wherein said second contact isa break contact serially interposed in said output circuit, said contactbeing opened near the end of said operating stroke of said device toextinguish said thyratron tube and de-energize said magnet.

References Cited in the file of this patent UNITED STATES PATENTS1,577,460 Franca Mar. 23, 1926 2,444,208 Taylor June 29, 1948 2,473,907Ridgeley -c June 21, 1949 2,651,729 Mavforth Sept. 8, 1953 2,714,842Hooven Aug. 9, 1955 OTHER REFERENCES Stephenson, 598,171, December 20,1949, an abstract, vol. 629, page 831 of the 0G. (December 20, 1949.)

1. IN COMBINATION WITH AN ELECTROMAGNETIC DEVICE HAVING A MAGNET, ANARMATURE ACTUATED BY SAID MAGNET AND FIRST AND SECOND CONTACTSCONTROLLED BY SAID ARMATURE: A SELF INTERRUPTING ARRANGEMENT FOR SAIDMAGNET INSURING COMPLETION OF BOTH THE OPERATING AND RELEASE STROKE OFSAID ARMATURE, SAID ARRANGEMENT COMPRISING A SOURCE OF POTENTIAL, ABISTABLE SWITCHING MEANS HAVING A CONTROL ELECTRODE, OUTPUT ELECTRODES,AND A CIRCUIT INCLUDING SAID OUTPUT ELECTRODES, SAID MAGNET, AND SAIDSECOND CONTACT, SAID FIRST CONTACT BEING ARRANGED TO OPERATE NEAR THEEND OF SAID RELEASE STROKE TO CONNECT SAID CONTROL ELECTRODE TO SAIDPOTENTIAL, SAID BISTABLE SWITCHING MEANS BEING SWITCHED TO ONE OF ITSSTATES IN RESPONSE TO THE LAST MENTIONED CONNECTION TO CAUSE SAID MAGNETTO BE ENERGIZED UNDER THE CONTROL OF SAID OUTPUT ELECTRODES, AND SAIDSECOND CONTACT BEING ARRANGED TO OPERATE NEAR THE END OF THE OPERATINGSTROKE OF SAID DEVICE TO SWITCH SAID SWITCHING MEANS TO ITS OTHER STATEAND DE-ENERGIZE SAID MAGNET.